JP2003124074A - Surface mount electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the material cost and the manufacturing cost of a surface mount electronic component by limiting a region for forming a gold-plated layer to the necessary minimum limit, while the effect of gold-plated on the outermost layer of a lead frame is sufficiently used in the electronic component comprising an electronic component element, a resin layer sheathing the element, and the lead frame of a folded plate shape obtained by drawing the outer end to the outside of the sheathing resin layer. SOLUTION: The surface mount electronic component comprises a first gold- plated layer provided to connect to the electronic component element, and a second gold-plated layer provided to connect to the external circuit substrate on the same surface side of a plate-like material for constituting the lead frame.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount electronic component which is surface mounted on a printed wiring board or the like.

[0002]

2. Description of the Related Art Surface-mounted electronic components, which are surface-mounted by a reflow soldering method or the like on a printed wiring board mounted on various electronic devices, have a sectional structure as shown in FIG. 3, for example.

This surface mount electronic component has a solid electrolytic capacitor element 1 as an electronic component element, an epoxy resin layer 2 for covering the solid electrolytic capacitor element, one end connected to the solid electrolytic capacitor element and the other end. Is provided with a pair of bent plate-shaped lead frames 51 and 52 that are drawn to the outside of the exterior resin layer.

In the solid electrolytic capacitor element 1, a surface of an anode body 11 made of a sintered material of tantalum powder, a dielectric film layer 12 obtained by electrolytically oxidizing the surface, a conductive polymer layer 13 as a cathode electrolyte, and graphite. The cathode extraction layer 14 composed of a layer and a silver paste layer is sequentially formed.
Anode lead pins 15 used for connection with the anode side lead frame 51 are planted in the anode body 11. The cathode lead layer 14 is provided for connection with the cathode side lead frame 52 via the conductive adhesive material 4.

One end 51 of the lead frames 51, 52
1, 521 are connected to the solid electrolytic capacitor element as described above, and the other ends 512, 522 are drawn to the outside of the exterior resin layer and bent to connect (solder) to the printed wiring board. Be served.

Regarding the soldering of electronic parts to a printed wiring board, in recent years, due to consideration for the natural environment,
Lead-free solder is being strongly promoted, and various alternative solder materials are being proposed or adopted, but the soldering temperature in that case is about 3 times that of conventional lead-tin solder.
It tends to be higher than 0 ° C.

As a lead frame for surface-mounted electronic components, a frame base material made of an iron-nickel alloy plated with lead-tin solder has been widely used. In lead-free reflow soldering at 260 ° C., the solder plating layer of the lead frame is melted by heat and a gap is formed between the solder plating layer and the exterior resin layer, impairing the airtightness and causing a problem in moisture resistance and the like.

As a measure against this, low melting point metal such as tin (melting point 232 ° C.) is removed from the plating material of the lead frame,
There is a movement to adopt only high melting point metals (melting point 400 ° C or higher). For example, a technique of forming a nickel plating layer (melting point 1450 ° C.) and a gold plating layer (melting point 1064 ° C.) on a frame base material made of an iron-nickel alloy is known.

In order to reduce the electric resistance, a copper plating layer (melting point 108) having a thickness of several μm is formed under the nickel plating layer.
3 ° C.) or to stabilize the solderability, a palladium plating layer (melting point 1) is formed under the gold plating layer.
The technique of forming 550 ° C.) is also known.

The gold plating layer [A] has the effect of making the solderability to the printed wiring board good and stable, that is, the effect of shortening the so-called "solder wetting time" and reducing its variation. In addition, there is an effect that the electrical resistance for connection is reduced and stabilized at a portion connected to the electronic component element via the conductive adhesive [B].

The inventor of the present application has the effect of forming the gold plating layer on the lead frame in the surface mount electronic component having the structure as shown in FIG. 3 (especially the above [B]).
The effect) was measured and confirmed.

That is, as the lead frames 51 and 52 in the configuration of FIG. 3, a copper plating layer having a thickness of 2 μm and a nickel plating having a thickness of 0.7 μm are formed on both surfaces of a plate-like frame base material made of 42 wt% nickel-iron alloy. Layer and thickness 0.
When using a 1 μm gold plating layer sequentially formed (conventional example 1), a 2 μm thick copper plating layer, 0.7 thickness
A solid electrolytic capacitor as a surface-mounted electronic component was manufactured using a structure in which a nickel plating layer having a thickness of 0.1 μm and a tin plating layer having a thickness of 0.1 μm were sequentially formed (conventional example 2), and an ESR (equivalent series connection) at 100 kHz was produced. Resistance) was measured. The results are shown in Table 1.

[0013]

[Table 1]

As can be seen from Table 1, in the conventional example 1 in which the outermost layer of the lead frame which is connected to the cathode extraction layer of the solid electrolytic capacitor element through the conductive adhesive is gold-plated, tin-plated is used. Compared with Conventional Example 2, the average value of ESR is about 6% smaller and the standard deviation is about 1/3.

This indicates that by applying gold plating to the outermost layer of the lead frame, the connection electric resistance of the solid electrolytic capacitor element with respect to the cathode extraction layer is obviously reduced, and in particular its variation is significantly reduced.

[0016]

DISCLOSURE OF THE INVENTION The present invention provides a region where a gold plating layer is formed while sufficiently exerting the above-mentioned effect ([A] [B]) obtained by plating the outermost layer of a lead frame. By minimizing the above, the material cost and the manufacturing cost of the surface mount electronic component are reduced.

[0017]

A surface mount electronic component according to the present invention comprises an electronic component element, a resin layer for packaging the electronic component element, one end connected to the electronic component element and the other end being the exterior package. In a surface mount electronic component including a bent plate-shaped lead frame extended to the outside of the resin layer, a first gold plating layer used for connection to the electronic component element is formed at one end of the lead frame. A second gold plating layer provided for connection to an external wiring board is formed on the other end of the lead frame, and the first and second gold plating layers are formed of a plate-shaped body that constitutes the lead frame. It is characterized in that they are formed on the same surface side.

According to such a lead frame structure, the effect of forming the gold plating layer on the portion used for connection to the electronic component element and the portion used for connection to the external wiring board is secured. However, since the gold plating layer forming region is on the same surface side (that is, only one surface side) of the lead frame, the material cost and the manufacturing cost of the surface mount electronic component can be reduced.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION A surface mount electronic component corresponding to one embodiment of the present invention has a sectional structure as shown in FIG.

This surface mount electronic component has a solid electrolytic capacitor element 1 as an electronic component element, an epoxy resin layer 2 for covering the solid electrolytic capacitor element, one end connected to the solid electrolytic capacitor element and the other end. Is provided with a pair of bent plate-shaped lead frames 31 and 32 extended to the outside of the exterior resin layer.

The solid electrolytic capacitor element 1 has a surface of an anode body 11 made of a sintered material of tantalum powder, a dielectric film layer 12 obtained by electrolytically oxidizing the surface, a conductive polymer layer 13 as a cathode electrolyte, and graphite. The cathode extraction layer 14 composed of a layer and a silver paste layer is sequentially formed.
Anode lead pins 15 used for connection with the anode side lead frame 31 are erected on the anode body 11. The cathode lead layer 14 is provided for connection with the cathode side lead frame 32 via the conductive adhesive material 4.

The lead frames 31, 32 are 42 w
A copper plating layer having a thickness of 2 μm and a nickel plating layer having a thickness of 0.7 μm are sequentially formed on both sides of a plate-shaped frame base material made of t% nickel-iron alloy, and the thickness is formed only on the nickel plating layer on one side. 0.1 μm gold plated layers 313, 323
Are formed.

One end 31 of the lead frames 31, 32
1, 321 are connected to the solid electrolytic capacitor element as described above, and the other ends 312, 322 are drawn to the outside of the exterior resin layer and bent to connect (solder) to the printed wiring board. Be served.

Due to the manufacturing method, the lead frames on the anode side and the cathode side are supplied in the form of a perforated ribbon 30 as shown in FIG. 2, and the solid electrolytic capacitor element 1 ( For simplification, only one piece is shown, and the anode side lead frame piece 310 and the anode lead pin of the solid electrolytic capacitor element are welded together, and the cathode side lead frame piece 320 and the cathode of the solid electrolytic capacitor element are led out. Bond the layers. The cathode-side lead frame piece is preliminarily bent at a portion indicated by reference numeral 324 according to the outer shape of the solid electrolytic capacitor element.

After that, the ribbon-shaped lead frame member 30
The solid electrolytic capacitor element 1 connected to the solid electrolytic capacitor is covered with an epoxy resin, and the ribbon-shaped lead frame member is cut along the broken lines P1 and P2, whereby the anode side lead frame piece and the cathode connected to the solid electrolytic capacitor element. The side lead frame pieces are separated from the ribbon-shaped lead frame member, both lead frame pieces are bent along the outer periphery of the exterior resin layer with the gold-plated layer forming surface facing outward, and as shown in FIG. The terminal portions 312 and 322 used for connection are formed.

Here, focusing on the relationship between the bonding surface of the cathode side lead frame to the solid electrolytic capacitor element and the outer surface of the outer resin layer bent along the outer periphery, conventionally, as shown in FIG. , In many cases, they were arranged on different sides (relationship between front and back). On the contrary,
In the embodiment of the present invention, the adhesion surface of the cathode side lead frame to the solid electrolytic capacitor element and the outer surface of the outer side of the outer resin layer which is bent along the outer periphery are the same side surface as shown in FIG.

In the folded structure of FIG. 3 (conventional example), the effects [A] and [B] of the gold plating layer described in the section of the prior art cannot be achieved unless the gold plating layers are formed on both surfaces of the lead frame. In the bending configuration of FIG. 1 (Example of the present invention), the effects [A] and [B] of the gold plating layer can be achieved by simply forming the gold plating layer on one surface of the lead frame. The cost required for formation can be reduced significantly.

In the bending structure shown in FIG. 1 (embodiment of the present invention), the lead frame is bent in a U shape with a relatively thin exterior resin layer sandwiched at a portion indicated by reference numeral 39. Although it is feared that the exterior resin layer will be damaged, it has been confirmed that no problem will occur if the root portion of the lead frame pulled out from the exterior resin layer is grasped and bent by an appropriate tool.

Further, in the above-mentioned ribbon-shaped lead frame member, in order to form the gold plating layer on only one surface, the other surface is masked and gold plating treatment is performed, but also on the surface on which the gold plating layer is formed. Since it is not necessary to form a gold plating layer on portions other than the portions to be separated as the lead frame pieces on the anode side and the cathode side (outside of the broken lines P1 and P2 in FIG. 2), if the portions are also masked at the same time, gold plating treatment may be performed. The area for forming the gold plating layer (that is, the amount of gold used) can be reduced to about 30% of the case where the gold plating layer is formed on both surfaces.

Even when the gold plating layers are formed on both surfaces, gold plating is not required except for the portion to be cut off as the lead frame piece. It doesn't lead to.

Although the case where the solid electrolytic capacitor element is used as the electronic component element has been described above as an example, the present invention can be applied to the case where another electronic component element such as a resistance element or a semiconductor element is used.

[0032]

According to the present invention, in a lead frame of a surface mount electronic component, a gold plating layer is formed at a portion used for connection to an external wiring board, so that solderability is good and stable. And the effect of stabilizing the connection electric resistance by forming a gold plating layer at the portion provided for connection to the electronic component element and stabilizing the same, while the gold plating layer forming region is formed on the same surface of the lead frame. Since it is on the side (that is, only on one side), the material cost and the manufacturing cost of the surface mount electronic component can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a surface mount electronic component according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a surface mount electronic component according to a conventional example.

FIG. 3 is a plan view of a lead frame member.

[Explanation of symbols]

1 Electronic component element (solid electrolytic capacitor element) 2 Exterior resin layer 31 Anode side lead frame 311 1st gold-plated layer of the lead frame on the anode side 312 2nd gold plating layer of the lead frame on the anode side 32 Cathode side lead frame 321 First gold plating layer of cathode side lead frame 322 Second gold plating layer of cathode side lead frame

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshiaki Namba             1-1-18 Okayama-Higashi, Shijo-Nawate City, Osaka Prefecture             Electronic Industry Co., Ltd. (72) Inventor Ryo Sakamaki             1-1-18 Okayama-Higashi, Shijo-Nawate City, Osaka Prefecture             Electronic Industry Co., Ltd. (72) Inventor Tadahito Ito             1-1-18 Okayama-Higashi, Shijo-Nawate City, Osaka Prefecture             Electronic Industry Co., Ltd. F-term (reference) 5E336 AA04 CC02 CC06 CC08 CC15                       CC19 CC53 EE01 GG05

Claims (3)

[Claims] 1. An electronic component element, a resin layer for covering the electronic component element, and a bent plate shape, one end of which is connected to the electronic component element and the other end of which is drawn out of the exterior resin layer. In a surface mount electronic component including a lead frame, a first gold plating layer used for connection to the electronic component element is formed at one end of the lead frame, and an external wiring is provided at the other end of the lead frame. A second gold-plated layer provided for connection to the substrate is formed, and the first and second gold-plated layers are formed on the same surface side of the plate-like body that constitutes the lead frame. Surface mount electronic components. 2. The lead frame has a structure in which a plate-shaped frame base material is covered with a plurality of plating layers, and the frame base material and the plating layer are both made of a metal having a melting point of 400 ° C. or higher. The surface mount electronic component according to claim 1, wherein 3. The electronic component element comprises a solid electrolytic capacitor element in which a dielectric film layer, a solid electrolyte layer, and a cathode extraction layer are sequentially formed on the surface of an anode body made of a metal material. The surface mount electronic component according to 1 or 2.